Human pathogenic gram-negative bacteria, such as Escherichia coli (E. Coli) and Salmonella enterica cause millions of deaths, thousands of fatalities and billions of dollars in medical expenses and lost wages. A critical process that enables these organisms to overcome the hosts immune response is the injection of proteins directly into infected mammalian (host) cells. Some of these injected effectors, function as enzymes that modify the structure/function of the host proteins, which in turn diminish the cells' ability to fight off the infection. One family of these enzymes are N-glycosyltransferases, which appear to play critical, but yet unknown, function in pathogenicity. These enzymes add a single ?-N-acetyl-D-glucosamine (GlcNAc) to the guanidinium groups of arginine residues. The primary focus of this application is to evaluate/develop methodology that will enable the generation of site-specific ?-N-GlcNAc antibodies. We feel that this ability will open the door to the creation of a wide range of Abs that will have a wide-ranging impact the fields of pharmacy, microbiology, and biochemistry.